The manufacture and frying of battered and other food products, can result in the creation of significant quantities of oil-laden and tat-laden crumbs, food particles and/or carbohydrate matrices. Although this invention applies to the separation and removal of oils and animal fats, for ease of reference, the terms oils or oil will be used herein and should be considered to refer to both oils and fats. Also, this invention applies to use for crumbs, carbohydrate matrices and food particles of all kinds, however, for ease of reference, the terms crumb or crumbs will be used generically to refer to all applications. Still further, while the solvent used to separate the oil from the crumb can be water or a solution of water and other compounds, an aqueous solution, the term water will be used generically to refer to water or an aqueous solution.
These crumbs can contain up to 75% oil by weight. The disposal of these crumbs, often as waste or low value by-product, results in a significant oil loss from the trying process. Experiments have shown that more than 95% of this oil can be recovered with little change in oil quality. It is this recovery that this invention is directed to.
Table 1 presents the results of an analysis of recovered oil samples. It shows an average increase in Percent Free Fatty Acid (%FFA) of 0.05% and an increase in Percent Moisture Content (%) of 0.65% when compared to oil samples taken from the fryer.
TABLE 1 ______________________________________ Oil Analysis Results Test Average Change ______________________________________ Percent Free Fatty Acid 0.05% (% FFA) Percent Moisture Content (%) 0.65% ______________________________________
In addition to the benefit of recovery of valuable cooking oil, there are other costs and problems associated with disposal of oil-laden crumbs which this invention can reduce or eliminate. If the crumbs are currently treated in a waste water treatment facility, clarifier loading can be reduced by eliminating part or all of this source of waste.
Landfilling crumbs, while an easy solution, adds disposal costs to the cost of replacing cooking oil which is discarded with the crumbs. Environmental concerns and increasingly restrictive regulations seem to indicate that landfilling crumbs may not be a long term viable option, or it may make the process economically unfeasible.
Merely disposing of the oil-laden crumbs is losing something of potential value. Table 2 shows the estimated value of the lost cooking oil based on hourly crumb production. The values are calculated based on a $2.00/gallon cooking oil replacement cost, and a conservative assumption that the crumbs contain 50% oil by weight. Analysis of crumbs produced by one commercial facility making battered french fries indicates that the actual oil content may average approximately 70%. The cost of recovering oil from crumbs will vary from one site to another but is estimated to be less than one cent per pound of recovered oil.
TABLE 2 ______________________________________ Estimated Daily Oil Loss Crumb production Oil lost daily Dollar value of oil [lb/hr] [gal/day] [$/day] ______________________________________ 800 1,300 2,600 1,000 1,650 3,300 1,200 2,000 4,000 ______________________________________
Prior attempts at the recovery of oil have generally resulted in an unacceptable recovery rate, for one or more of a number of different problems, namely: they result in the formation of an emulsion instead of separation of the oil or fat from the crumb or food particle material; they do not recover a high percentage of the oil contained in the crumb; they discharge too much waste; they have been unable to provide such a process or device which is relatively inexpensive to construct and operate; and they have been unable to provide a system that operates effectively when wide variations in the composition of the feedstock occur.
The normal waste from these manufacturing processes is waste grade oil or grease and normally has a value, if any, of only two or three cents per pound, whereas food grade oil has an approximate value range of thirty to forty cents per pound. This invention provides a means to recover the same quality of oil that exists in the original matrix prior to treatment, thereby having substantially more value to the manufacturer.
This invention solves the forenamed problems to a degree not heretofore achieved on any scale, let alone for a commercial production unit capable of continuous production.